This application claims priority under 35 USC 119(a) to Patent Application No. 2003-147821 filed in Japan on 26 May 2003, the content of which is incorporated herein by reference in its entirety.
The present invention pertains to light emitting semiconductor device(s) used for photography in the context of camera(s) employing silver halide film(s), digital camera(s) carrying out recording in electronic fashion, and so forth; and pertains to photographic illumination apparatus(es) employing same.
Stroboscopic lamps in which electrical discharge tubes filled with xenon (Xe) gas are made to emit light are commonly employed as conventional photographic illumination apparatuses. As stroboscopic lamps of this type require circuits for increasing voltage, circuits for modulating light, and/or other complicated circuits, reduction in size and reduction in cost are believed to be difficult to achieve. Furthermore, because such stroboscopic lamps employ high-capacitance capacitors, there is also the problem that the large amount of time required for charging thereof can result in lost photographic opportunities. Moreover, in order to set irradiative locus or loci so as to be compatible with field angle(s) of photographic lens(es) it is necessary to insert lens(es) and/or other such optical component(s) to the front of photographic illumination apparatus(es) and/or alter distance(s) between electrical discharge tube(s) and reflector(s) and/or to furthermore alter dimension(s) of reflector(s) to the rear thereof, and/or carry out similar measures for accommodation of same.
In conjunction with the increased brightness of modern light emitting diodes (hereinafter “LEDs”), light emitting semiconductor devices employing, as light sources, LEDs such as that shown in FIG. 5—so-called LAMP-type (artillery-shell-shaped) LEDs—have been used in photographic illumination apparatuses as means for solving the foregoing problems.
At the light emitting semiconductor device (LAMP-type LED) shown in FIG. 5, LED element 101 is provided at bowl-shaped recess 105 in frame 103 by way of electrically conductive paste 102, this LED element 101 being connected to frame 104 by way of Au lead 106. In addition, the LED package is constructed such that the internal components are covered by phototransmissive resin 107 having surface(s) which is/are curved in cup-like fashion. Light emitted toward the back and/or side(s) of LED element 101 is reflected toward the front by the surface of recess 105. When such reflected light exits and passes to the exterior of resin 107, the round resin shape at the front thereof causes the light to be refracted and condensed.
As an example of a photographic illumination apparatus employing light emitting semiconductor device(s) of configuration as shown in FIG. 5, Japanese Patent Application Publication Kokai No. 2002-207236 (hereinafter “Patent Reference No. 1”) discloses a photographic illumination apparatus for a camera which is constituted as shown in FIG. 6.
At FIG. 6, photographic illumination apparatus 109 of camera 108 is made up of a plurality of light emitting semiconductor devices 110. At this photographic illumination apparatus 109, adjustment of illumination intensity is carried out by varying the number of light emitting semiconductor devices 1 10 that are made to emit light and/or the amount of light emitted thereby in accordance with distance to photographic subject and/or film sensitivity. Furthermore, by arraying plurality of light emitting semiconductor devices 110 such that they are respectively displaced somewhat relative to the optical axis of photographic lens 111, and/or by arranging some number of light emitting semiconductor device(s) 110 in separated fashion, it has also been possible to adopt methods of light emission consistent with distance to photographic subject.
However, with photographic illumination apparatuses employing light emitting semiconductor devices such as are indicated at Patent Reference No. 1, because it has been impossible to array multiple light emitting diode elements at a single focal position, this has, rather, resulted in the problem of poor light-condensing characteristics. As a result, there has been occurrence of circumstances tending to cause color balance to deteriorate, resulting in so-called chromatic shift, with increasing proximity to the periphery of the light-emitting unit. Furthermore, with the foregoing conventional photographic illumination apparatuses, while there has been improvement in uniformity of radiant intensity over the irradiative locus, there has been limited ability to change the irradiative locus itself in correspondence to changes in field angle for accommodation of wide-angle or telephoto photography and the like.
The present invention was therefore conceived in order to solve the foregoing problems, it being an object thereof to provide a light emitting semiconductor device, and photographic illumination apparatus employing same, permitting prevention of occurrence of chromatic shift and making it possible to ensure appropriate irradiation consistent with photographic lens field angle size.